content/browser/android/overscroll_glow.h

   1 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #ifndef CONTENT_BROWSER_ANDROID_OVERSCROLL_GLOW_H_
   6 #define CONTENT_BROWSER_ANDROID_OVERSCROLL_GLOW_H_
   7
   8 #include "base/memory/ref_counted.h"
   9 #include "base/memory/scoped_ptr.h"
  10 #include "base/time/time.h"
  11 #include "ui/gfx/geometry/size_f.h"
  12 #include "ui/gfx/geometry/vector2d_f.h"
  13
  14 namespace cc {
  15 class Layer;
  16 }
  17
  18 namespace content {
  19
  20 class EdgeEffectBase;
  21
  22 // Provides lazy, customized EdgeEffect creation.
  23 class OverscrollGlowClient {
  24  public:
  25   virtual ~OverscrollGlowClient() {}
  26
  27   // Called lazily, after the initial overscrolling event.
  28   virtual scoped_ptr<EdgeEffectBase> CreateEdgeEffect() = 0;
  29 };
  30
  31 /* |OverscrollGlow| mirrors its Android counterpart, OverscrollGlow.java.
  32  * Conscious tradeoffs were made to align this as closely as possible with the
  33  * original Android Java version.
  34  */
  35 class OverscrollGlow {
  36  public:
  37   enum Edge { EDGE_TOP = 0, EDGE_LEFT, EDGE_BOTTOM, EDGE_RIGHT, EDGE_COUNT };
  38
  39   // |client| must be valid for the duration of the effect's lifetime.
  40   // The effect is enabled by default, but will remain dormant until the first
  41   // overscroll event.
  42   explicit OverscrollGlow(OverscrollGlowClient* client);
  43   ~OverscrollGlow();
  44
  45   // Called when the root content layer overscrolls.
  46   // |accumulated_overscroll| and |overscroll_delta| are in device pixels, while
  47   // |velocity| is in device pixels / second.
  48   // |overscroll_location| is the coordinate of the causal overscrolling event.
  49   // Returns true if the effect still needs animation ticks.
  50   bool OnOverscrolled(base::TimeTicks current_time,
  51                       const gfx::Vector2dF& accumulated_overscroll,
  52                       gfx::Vector2dF overscroll_delta,
  53                       gfx::Vector2dF velocity,
  54                       const gfx::Vector2dF& overscroll_location);
  55
  56   // Returns true if the effect still needs animation ticks, with effect layers
  57   // attached to |parent_layer| if necessary.
  58   // Note: The effect will detach itself when no further animation is required.
  59   bool Animate(base::TimeTicks current_time, cc::Layer* parent_layer);
  60
  61   // Update the effect according to the most recent display parameters,
  62   // Note: All dimensions are in device pixels.
  63   void OnFrameUpdated(const gfx::SizeF& viewport_size,
  64                       const gfx::SizeF& content_size,
  65                       const gfx::Vector2dF& content_scroll_offset);
  66
  67   // Reset the effect to its inactive state, clearing any active effects.
  68   void Reset();
  69
  70   // Whether the effect is active, either being pulled or receding.
  71   bool IsActive() const;
  72
  73   // The maximum alpha value (in the range [0,1]) of any animated edge layers.
  74   // If the effect is inactive, this will be 0.
  75   float GetVisibleAlpha() const;
  76
  77  private:
  78   enum Axis { AXIS_X, AXIS_Y };
  79
  80   // Returns whether the effect has been properly initialized.
  81   bool InitializeIfNecessary();
  82   bool CheckNeedsAnimate();
  83   void UpdateLayerAttachment(cc::Layer* parent);
  84   void Detach();
  85   void Pull(base::TimeTicks current_time,
  86             const gfx::Vector2dF& overscroll_delta,
  87             const gfx::Vector2dF& overscroll_location);
  88   void Absorb(base::TimeTicks current_time,
  89               const gfx::Vector2dF& velocity,
  90               bool x_overscroll_started,
  91               bool y_overscroll_started);
  92   void Release(base::TimeTicks current_time);
  93
  94   EdgeEffectBase* GetOppositeEdge(int edge_index);
  95
  96   OverscrollGlowClient* const client_;
  97   scoped_ptr<EdgeEffectBase> edge_effects_[EDGE_COUNT];
  98
  99   gfx::SizeF viewport_size_;
 100   float edge_offsets_[EDGE_COUNT];
 101   bool initialized_;
 102   bool allow_horizontal_overscroll_;
 103   bool allow_vertical_overscroll_;
 104
 105   scoped_refptr<cc::Layer> root_layer_;
 106
 107   DISALLOW_COPY_AND_ASSIGN(OverscrollGlow);
 108 };
 109
 110 }  // namespace content
 111
 112 #endif  // CONTENT_BROWSER_ANDROID_OVERSCROLL_GLOW_H_